There are route searching apparatuses in the known art that search the optimal route along which the vehicle is to be guided to the destination and search a route for detouring part of the guided route obtained through the search as necessary. In such an apparatus, the detour route search is performed either in an automatic mode, in which the detour route search processing is automatically executed based upon traffic information obtained from an outside source such as a VICS (vehicle information and communication system) or in a manual mode, in which an occupant executes the detour route search processing at any time and at any location. In the automatic mode, traffic information regarding traffic jams, traffic control and construction work in progress and the like is obtained from, for instance, the VICS and a detour route search for detouring a road segment where the traffic is jammed or controlled or construction work is in progress is automatically executed. In the manual mode, the occupant who is aware of a road segment on the guided route where the traffic is jammed or controlled, or construction work is in progress specifies a distance over which the guided route should be detoured starting from the current position by ensuring that the road segment is contained within the specific distance and executes a detour route search in order to detour the guided route over the specified distance. It is to be noted that the detour route search must always be performed in the manual mode in countries and regions where traffic information from the VICS or the like is not available.
In the manual detour route search mode in route searching apparatuses in the related art, the occupant must be aware of the segments over which the guided route should be detoured and execute a detour route search by specifying the distance from the current position which contains the segment to be detoured. Accordingly, it is difficult to correctly specify the distance, which contains the detour segment in a timely manner when the driver wishes to detour the guided route, and there is another problem in that since it is necessary for the occupant to perform the operation of specifying the distance, the operability becomes poor.